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<\/a><\/span>Some time ago researchers proposed that the modern DNA signal indicated that chimps and humans continued to interbreed long after they split in evolutionary time. A new study refutes this, and as the author states, this new study is more correct because it “simpler and hence more likely”.<\/p>\nWow. When the study’s author states that this is more likely to be true because it is the simpler explanation, it makes me laugh. This, of course, is the invocation of the parsimony principle, which many people believe states that the simplest answer is the most likely to be true. But of course, biological systems, events, and scenarios tend to be complex, so this is not a valid guideline. Rather, explanations that are unnecessarily complex tend to have more wrong things in them.<\/p>\n Anyway, getting back to the main point of the study, which in the recently released nature piece is all mucked up with iffy reporting and strange logic by the scientists …<\/p>\n In 2006, David Reich and his colleagues at the Broad Institute in Cambridge, Massachusetts, compared the genomes of humans, chimps and three other primate species, and found that the separation of ancient humans from our closest cousins was more complex than a clean break. The time from the beginning to the completion of human-chimp divergence ranged over more than four million years across different parts of the genome, and the X chromosome seemed youngest of all,…<\/p><\/blockquote>\n Which, honestly, nobody believed.<\/p>\n Now, we have this: Other researchers …<\/p>\n \n…have reanalysed the data and suggest that species differences in the levels of female promiscuity can account for the chromosomal inconsistency. The original hypothesis is “way more of a headache for evolutionary biologists”, says Yi. The data “can also be explained very well by well-established ideas in molecular evolution”.<\/p><\/blockquote>\n Here’s my thinking on this: The issue comes down to the historical ‘behavior’ of genes on autosomes vs. sex chromosomes. Using this as data is potentially dangerous. If we had an adequate convincing not-out-of-your-ass theory for how sex chromosomes come to be, then maybe we could use this information, but at the moment we are using a system that is not even close to well understood.<\/p>\n Sources:<\/p>\n Presgraves, D., & Yi, S. (2009). Doubts about complex speciation between humans and chimpanzees Trends in Ecology & Evolution<\/span> DOI: 10.1016\/j.tree.2009.04.007<\/a><\/span><\/p>\n Dolgin, Elie (2009). Human-chimp interbreeding challenged Nature News<\/span><\/span><\/p>\n","protected":false},"excerpt":{"rendered":" Yes, but not necessarily because it is wrong. Some time ago researchers proposed that the modern DNA signal indicated that chimps and humans continued to interbreed long after they split in evolutionary time. A new study refutes this, and as the author states, this new study is more correct because it “simpler and hence more … Continue reading Is the latest claim regarding “chimp-human” inbreeding a bunch of hooey?<\/span>
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\nLet us begin at the beginning: There was no interbreeding between chimps and humans. not even “early humans,” because they did not exist yet, so when Elie Dolgin (or a Nature editor? Henry?) makes this statement: “A genetic analysis has called into question the controversial claim that early humans and chimpanzees interbred before splitting into separate species.” [source<\/a>] they are walking on thin ground riddled with falsehoods<\/a>.<\/p>\n